1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
/*
* arch/ubicom32/include/asm/uaccess.c
* User space memory access functions for Ubicom32 architecture.
*
* (C) Copyright 2009, Ubicom, Inc.
*
* This file is part of the Ubicom32 Linux Kernel Port.
*
* The Ubicom32 Linux Kernel Port is free software: you can redistribute
* it and/or modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, either version 2 of the
* License, or (at your option) any later version.
*
* The Ubicom32 Linux Kernel Port is distributed in the hope that it
* will be useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with the Ubicom32 Linux Kernel Port. If not,
* see <http://www.gnu.org/licenses/>.
*
* Ubicom32 implementation derived from (with many thanks):
* arch/m68knommu
* arch/blackfin
* arch/parisc
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/module.h>
#include <asm/segment.h>
#include <asm/uaccess.h>
extern int _stext, _etext, _sdata, _edata, _sbss, _ebss, _end;
/*
* __access_ok()
* Check that the address is in the current processes.
*
* NOTE: The kernel uses "pretend" user addresses that wind
* up calling access_ok() so this approach has only marginal
* value because you wind up with lots of false positives.
*/
int __access_ok(unsigned long addr, unsigned long size)
{
// struct vm_area_struct *vma;
/*
* Don't do anything if we are not a running system yet.
*/
if (system_state != SYSTEM_RUNNING) {
return 1;
}
/*
* It appears that Linux will call this function even when we are not
* in the context of a user space application that has a VM address
* space. So we must check that current and mm are valid before
* performing the check.
*/
if ((!current) || (!current->mm)) {
return 1;
}
/*
* We perform some basic checks on the address to ensure that it
* is at least within the range of DRAM.
*/
if ((addr < (int)&_etext) || (addr > memory_end)) {
printk(KERN_WARNING "pid=%d[%s]: range [%lx - %lx] not in memory area: [%lx - %lx]\n",
current->pid, current->comm,
addr, addr + size,
memory_start, memory_end);
return 0;
}
/*
* For nommu Linux we can check this by looking at the allowed
* memory map for the process.
*
* TODO: Since the kernel passes addresses in it's own space as though
* they were user address, we can not validate the addresses this way.
*/
#if 0
if (!down_read_trylock(¤t->mm->mmap_sem)) {
return 1;
}
vma = find_vma(current->mm, addr);
if (!vma) {
up_read(¤t->mm->mmap_sem);
printk(KERN_WARNING "pid=%d[%s]: possible invalid acesss on range: [%lx - %lx]\n",
current->pid, current->comm, addr, addr + size);
return 1;
}
if ((addr + size) > vma->vm_end) {
up_read(¤t->mm->mmap_sem);
printk(KERN_WARNING "pid=%d[%s]: possible invalid length on range: [%lx - %lx]\n",
current->pid, current->comm, addr, addr + size);
return 1;
}
up_read(¤t->mm->mmap_sem);
#endif
return 1;
}
EXPORT_SYMBOL(__access_ok);
|
